2.8.10 Expression productions

ConstExpr = Expr.

Expr = E1 {OR E1}.
  E1 = E2 {AND E2}.
  E2 = {NOT} E3.
  E3 = E4 {Relop E4}.
  E4 = E5 {Addop E5}.
  E5 = E6 {Mulop E6}.
  E6 = {"+" | "-"} E7.
  E7 = E8 {Selector}.
  E8 = Id | Number | CharLiteral | TextLiteral
     | Constructor | "(" Expr ")".

Relop =  "=" | "#" | "<"  | "<=" | ">" | ">=" | IN.
Addop =  "+" | "-" | "&".
Mulop =  "*" | "/" | DIV | MOD.

Selector = "^"  |  "." Id  |  "[" Expr {"," Expr} "]"
         | "(" [ Actual {"," Actual} ] ")".

Constructor = Type "{" [ SetCons | RecordCons | ArrayCons ] "}".

SetCons = SetElt {"," SetElt}.
SetElt = Expr [".." Expr].
RecordCons = RecordElt {"," RecordElt}.
RecordElt = [Id ":="] Expr.
ArrayCons =  Expr {"," Expr} ["," ".."].